The genomics group at Southwestern Medical Center is committed to the generation of new M13 and PAC (or BAC) libraries specific for chromosome 15. The M13 constructs will be used in conjunction with radiation hybrids to substantially improve the density of existing STS maps. PAC libraries, newly constructed chromosome-specific and original whole genome versions, will be used to establish sequence-ready contigs of the chromosome. Both the M13 and PAC libraries will be constructed using blunt end ligation of DNA prepared from flow-sorted chromosomes. Future efforts will require the optical sorter operating at 30 to 50 times the rate of conventional sorters to generate the amount of chromosomes required for this project.